chore(runtime): close Wave 3 review nits

tests/test_wave3_browser_platform.py

@@ -0,0 +1,21 @@
+"""Wave 3 metadata requires a real allowlisted Linux producer artifact."""
+import pytest
+from src import browser_identity as browser
+from src.agent_runtime.resources import ResourceIdentityError
+
+
+@pytest.mark.parametrize('system,machine', [('Darwin', 'x86_64'), ('Darwin', 'arm64'),
+    ('Windows', 'AMD64'), ('Windows', 'ARM64'), ('Linux', 'riscv64')])
+async def test_unsupported_platform_fails_before_producer_execution(monkeypatch, system, machine):
+    monkeypatch.setattr(browser.platform, 'system', lambda: system)
+    monkeypatch.setattr(browser.platform, 'machine', lambda: machine)
+    async def forbidden(*args, **kwargs): pytest.fail('Unsupported producer was executed')
+    monkeypatch.setattr(browser, 'run_client', forbidden)
+    with pytest.raises(ResourceIdentityError, match='Unsupported browser producer platform'):
+        await browser.trusted_producer()
+
+
+def test_observed_release_hash_contract_is_explicit():
+    assert set(browser.PRODUCER_HASHES) == {'linux-x64', 'linux-arm64'}
+    assert browser.PRODUCER_VERSION == '0.35.0'
+    assert browser.SESSION_ACTIONS == {'session_info'}